Aircraft trajectory definition is an important task that flight managers have to face in order to reach some scheduled goals related to certain figures of merit (FOM'S).
When establishing which aircraft trajectory is to be considered the best one for a flight between two geographic positions, there is no unique criterion for defining what is “the best trajectory”, therefore existing different criteria, according to which, different aircraft trajectories might be simultaneously considered “the best one”, it depending on which goal is to be considered the main target to be accomplished by a certain flight.
These goals, also called “Figures of Merit” (FOM's), are defined in terms of cost saving, time saving, distance saving, or any task that a flight manager might establish.
Therefore, it appears obvious that an aircraft trajectory which might be considered the best one in terms of time saving for a flight between two geographical positions, might not be the best one in terms of cost saving, and vice versa.
The problem of choosing the most suitable trajectory according to the FOM to be optimized increases its complexity when taking into account the weather conditions in the different segments of the flight trajectory in which the aircraft is to be flying.
Weather conditions can substantially affect the performance of the aircraft during the flight and the achievement of the proposed goals, so it is extremely convenient, when not even compulsory, to avoid the areas in which storms or strong winds are forecasted, or at least being able to determine in what extent do these meteorological aspects affect the achievement of certain FOM's in certain trajectories.
With these regards, flight managers currently take into account weather conditions in a deterministic manner, i.e. they analyze a unique forecast which is considered valid for a large region and for a long period of time, therefore not profiting from the current available numeric model forecasts, which contemplate different possible forecasts, assigning to each of said forecasts a certain probability.
The uncertainty associated with the weather forecast is considered to be the biggest source of uncertainty influencing the definition and prediction of the aircraft trajectory during a flight.
That is, if we are looking forward to know which trajectory might be the best one in terms of cost saving (the cheapest one), and we do not consider several weather scenarios, then, the uncertainty in a chosen trajectory being indeed the cheapest one is big.
Therefore, there is a current concern in flight management in managing many uncertainty sources so as to reduce their associated uncertainty, avoiding uncertainty spread into predicted trajectories.